Non-free radical polymerizations of ethylenically-unsaturated monomers are well known. Typically, these polymerizations use catalysts instead of initiators to effect polymerizations. Examples of such catalyzed polymerizations include Ziegler-Natta (ZN) polymerizations of alpha-olefins, ring-opening metathesis polymerizations (ROMP) of cyclic olefins, group-transfer polymerizations (GTP), and cationic and anionic polymerizations of activated olefins such as styrene or acrylate esters. More recently, metallocene catalysts have received considerable attention for polymerization of alpha-olefins. ZN and metallocene catalysts for alpha-olefin polymerizations are susceptible to deactivation by adventitious oxygen and water, requiring that such deactivating materials be rigorously excluded from all reagents as well as the reaction vessel.
European Patent Application No. 454231 describes a polymerization catalyst and a method of polymerizing ethylene, other olefins, and alkynes using a polymerization catalyst whose cationic portion has the formula EQU LM--R.sup.+
wherein M is a Group VIII metal, L is a ligand or ligands stabilizing the Group VIII metal, and R is H, a hydrocarbyl radical or a substituted hydrocarbyl radical, and a substituted tetraphenylborate anion as the counterion. A preferred cationic portion has the formula ##STR1## wherein L' is a two-electron donor ligand and ##STR2## are chelating ligands wherein each L" is a neutral two-electron donor ligand, and M is nickel or palladium. All olefin polymerizations were conducted with ethylene, were carried out under dry, oxygen-free nitrogen atmospheres and all solvents were thoroughly dried under nitrogen by distillation from, e.g., sodiun/benzophenone. High polymer (M.sub.w &gt;90,000) was not disclosed.
Johnson et al., (J Am. Chem. Soc., 1995, 117, 6414-6415 and supplementary material) describe Pd(II)- and Ni(II)-based catalysts for alpha-olefin polymerizations wherein the catalysts are, for example, cationic metal methyl complexes of the general formula EQU {(ArN.dbd.C(R.sup.1)C(R.sup.1).dbd.NAr)M(CH.sub.3)(OEt.sub.2) }.sup.+ {BAr'.sub.4 }.sup.-
wherein M is Pd or Ni, Ar' is 3,5-C.sub.6 H.sub.3 (CF.sub.3).sub.2, Ar is 2,6-C.sub.6 H.sub.3 (R') where R' is isopropyl or methyl; R.sup.1 is H, methyl, or the two R.sup.1 groups taken together are 1,8-naphthalene-diyl. All polymerizations were carried out in inert atmospheres, and polymers of ethylene, propene, and 1-hexene are reported. The same authors and S. J. McLain et al. reported that the same catalysts copolymerized ethylene and methyl acrylate (see PMSE Abstracts, Vol. 73, p. 458, Fall 1995, Proceedings of the American Chemical Society, Fall 1995, Chicago, Ill.). A full publication describing these findings and a catalyst {(ArN.dbd.C(R.sup.1)C(R.sup.1).dbd.NAr)M(CH.sub.2 CH.sub.2 CH.sub.2 C(OR.sup.2)(C.dbd.O))}.sup.+ BAr'.sub.4.sup.- are reported by Johnson et al. (J. Am. Chem. Soc., 1996, 118, 267-268 and supplementary material), wherein R.sup.2 can be --CH.sub.3, t-butyl, or --CH.sub.2 (CF.sub.2).sub.6 CF.sub.3, and R.sup.1, Ar, and Ar' are as defined above. These findings also appeared in M. Brookhart, L. K. Johnson, C. M. Killian, S. Mecking, D. J. Tempel, Polymer Preprints, 1996, 37, 254-255.
These catalysts were prepared in a multi-step sequence shown in Scheme I, below. The ligand (ArN.dbd.C(R.sup.1)C(R.sup.1).dbd.NAr) (III) was prepared from 2,6-diisopropylaniline (II) and 1,2-dione O.dbd.C(R.sup.1)C(R.sup.1).dbd.O (I), optionally in the presence of formic acid (H. T. Dieck, M. Svoboda, T. Greiser Z. Naturforsch. 36b, 1981, 823-832.). In a separate procedure, (1,5-cyclooctadiene)PdCl.sub.2 (IV) was reacted with Me.sub.4 Sn to give (1,5-cyclooctadiene)PdCl (Me) (V) (R. Rulke, J. M. Emnsting, A. L. Spek, C. . Elsevier, P. W. N. M. van Meeuwen, K. Vrieze Inorg Chem., 1993, 32, 5769-5778). The ligand (ArN.dbd.C(R.sup.1)C(R.sup.1).dbd.NAr) (III) and (1,5-cyclooctadiene) PdCl (Me) (V) were then reacted to give neutral organometallic compound (ArN.dbd.C(R.sup.1)C(R.sup.1).dbd.NAr)PdCl(Me) (VI) (described in the previously cited Johnson et al., J. Am. Chem. Soc., 1995, 117, 6414-6415 and supplementary material ). This compound was further reacted with MgMe.sub.2 to give (ArN.dbd.C(R.sup.1)C(R.sup.1).dbd.NAr)Pd(Me).sub.2 (VII). In a separate procedure, NaB{3,5-C.sub.6 H.sub.3 (CF.sub.3).sub.2 }.sub.4 (IX) was synthesized by treating {Br-3,5-C.sub.6 H.sub.3 (CF.sub.3).sub.2 } (VIII) with Mg, and reacting the product with NaBF.sub.4 (M. Brookhart, B. Grant, A. F. Volpe, Jr. Organometallics 1992, 11, 3929-3922). CAUTION: This preparation of this salt is particularly hazardous in that trifluoromethyl aryl Grignards can explode (E. Hauptman, R. M. Waymouth, J. W. Ziller J. Am. Chem. Soc., 1995, 117, 11586-11587). Then Na{B(3,5-C.sub.6 H.sub.3 (CF.sub.3).sub.2).sub.4 } (IX) was converted to {H(OEt.sub.2).sub.2 }.sup.+ {B(3,5-C.sub.6 H.sub.3 (CF.sub.3).sub.2).sub.4 }.sup.- (X). Finally, {H(OEt.sub.2).sub.2 }.sup.+ {B(3,5-C.sub.6 H.sub.3 (CF.sub.3).sub.2).sub.4).sup.- (X) and (ArN.dbd.C(R.sup.1)C(R.sup.1).dbd.NAr)Pd(Me).sub.2 (VII) were reacted to give {(ArN.dbd.C(R.sup.1)C(R.sup.1).dbd.NAr)M(CH.sub.3)(OEt.sub.2)}.sup.+ {B(3,5-C.sub.6 H.sub.3 (CF.sub.3).sub.2).sub.4 }.sup.- (XI). ##STR3##
In Scheme I, R.sup.1 is H or methyl, or the two R.sup.1 s taken together are 1,8-naphthalene-diyl, i.e., ##STR4## the ligand made from acenaphthenequinone; and "COD" refers to 1,5-cyclooctadiene.
U.S. Pat. No. 5,296,566 describes certain organometallic catalysts for ROMP of ring-strained cyclic olefins that are stable towards oxygen and water. However, these catalysts are ineffective for polymerization of linear alpha-olefin monomers.
Safir et al. (Macromolecules, 1995, 28, 5396-5398) describe bicyclic olefin polymerizations catalyzed by Pd(II)-alkyl complexes such as, e.g., hexafluoroacetylacetonato-.sigma., .pi.-(2-acetylbicyclo{2.2.1}hepta-5-ene), related dimers, and (bicyclo{2.2.1}hepta-2,5-diene)PdCl.sub.2, wherein the catalysts are reported to be stable to both air and moisture for extended periods, and are reported to catalyze olefin insertion polymerization of bicyclic olefins such as, e.g., norbornene. Polymerizations of alpha-olefins, even ethylene (the most reactive of the alpha-olefins), are not reported.
Japanese Patent Application No. JP 0725932 describes Group VIII catalysts (such as Ni) which polymerize ethylene. U.S. Pat. No. 4,724,273 describes the use of nickel catalysts to polymerize alpha-olefins, yielding polymers with methyl branching points. U.S. Pat. No. 5,030,606 describes nickel-containing catalysts which are useful for producing copolymers of ethylene and polar or non-polar comonomers.
European Patent Application No. 603,557 describes catalytic compositions prepared by contacting an organonickel compound with a cyclicazacarbyl compound which can be used to convert one or more olefins to oligomerization and/or polymerization products. Only ethylene is exemplified.